Temperature regulation and metabolism Heterothermy Daily Seasonal Myotis Tenrec Bradypus Macaca Homeothermy
Costs of Endothermy metabolic response to temperature extremes Ambient temperature low high
Metabolic rate and body size SMALL MAMMALS Larger relative surface area Higher rates of heat exchange
Coping with seasonal environments -- Migration Lasiurus cinerea Lasionycteris noctivagans Lasiurus cinerea
COPING WITH COLD Subnivean zone -30° -20° -10° 0° Snow surface Temperature profile Mouse runways gopher “eskers”
Heterothermy Homeothermy Eptesicus fuscus Thermal neutral zone
Heterothermy -- Daily torpor Chaetodipus californicus 10 h torpor bout
Heterothermy -- Daily torpor 85% energy savings
Seasonal heterothermy Hibernation (winter dormancy) Spermophilus parryii arousal bout
Seasonal heterothermy Hibernation + Aestivation (winter + summer dormancy) Spermophilus mollis Active 4 months (spring growing season) Dormant 8 months (hottest AND coldest months)
Temperature (°C) Soil temperature profile -- Great Basin
Ammospermophilus leucurus Year-round daytime activity BUT Seasonal shift in behavior Behavioral & Physiological tolerance August January COPING WITH HEAT Summer heat avoidance Surface activity bouts (and resting in shade) underground Daily activity profile (mid-summer)
Desert Animals Potential evaporative water loss SMALL MAMMALS Larger relative surface area 1)Higher heat loads 2)Higher evaporative loss
Burrow microclimate Sundevall’s Jird (Meriones crassus) Negev Desert, Israel Daytime (underground) Temperature Burrow Surface Relative Humidity Burrow Surface Mid-summer profiles
Water conservation in desert rodents Merriam’s Kangaroo rat (Dipodomys merriami) Southwestern US
Water conservation in desert rodents Ord’s kangaroo rat (Dipodomys ordii) Western US
Kidney structure and water conservation Dilute Concentrated 1200 medulla
Dromedary (Camelus Dromidarius) Bactrian Camel (Camelus bactrianus) Guanaco (Lama guanaco) Desert adaptations in large mammals (Camelidae)
Keeping the brain cool Countercurrent heat exchange Keeping extremities warm
Marine mammals Temperature regulation
depth (m) duration (min) Humans skin diver scuba 300 Deep Diving Human technology attack submarine test depth 400 “crush” depth 600 research submarine Alvin 4,500 bathyscaphe Trieste 10,912 Otariidae fur seal sea lion Phocidae Harbor seal Weddell seal Elephant seal 1, Whales Fin whale Pilot wale 610 Beluga Killer whale 1,000+ Sperm whale (feeding) (record) 3, (maximum) ?
DEEP DIVING feeding dives of sperm whale (Physeter macrocephalus )
Elephant Seal Diving AnimalsDivesDuration (min) Surface Interval (min) Mean MaxMean 21 Females 116, Males100, Depth (m) Mean Max DEEP DIVING -- feeding dives of elephant seal (Mirounga angustirostris)
DIVING PROBLEMS Problem 1 -- Oxygen supply Physiological adaptations: Increased blood volume & hematocrit more hemoglobin and myoglobin selective shunting of blood, lower heart rate lower metabolic expenditure higher tolerance of CO2 & lactic acid
Phoca vitulina (common harbor seal) DEEP DIVING Diving Bradycardia - lower heart rate, blood diverted to essential organs From: Elsner (1988)
DEEP DIVING Reduced energy expenditure during dive Passive gliding descent Active stroking (Mirounga angustirostris)
Problem 3 -- Nitrogen Decompression sickness the “bends” Nitrogen narcosis DIVING PROBLEMS Problem 2 – Water pressure
Sperm whale (Physeter macrocephalus) Spermaceti organ Possible functions: Hydrostatic Echolocation Weapon (ram)
DIVING PROBLEMS Problem 4 -- Navigation Foraging at depths where there is little or no ambient light Toothed whales sophisticated underwater sonar Seals -- Don’t have echolocation Acute “passive” hearing High visual acuity Sensitive tactile vibrissae